Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:6.3.5.5 (CPS)
 1,262 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The carAB operon, encoding carbamoylphosphate synthetase (CPSase; EC 6.3.5.5) is transcribed from two tandem promoters. The upstream promoter (P1) is controlled by pyrimidines and the downstream promoter (P2) is controlled by arginine. We have isolated a new type of constitutive mutation (carP) that specifically affects the control of the pyrimidine-sensitive promoter but does not appear to influence other genes of the pyrimidine pathway. The carP mutation acts in trans and is dominant, which suggests that the carP product is an activator of car transcription. The downstream promoter P2, which is repressed by arginine, overlaps two operator modules characteristic of the arginine regulon. We have isolated two operator-constitutive mutations that specifically affect P2; both map in the upstream ARG box at a strongly conserved position.
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PMID:carP, a novel gene regulating the transcription of the carbamoylphosphate synthetase operon of Escherichia coli. 306 18

Current methodologies for the assessment of urea cycle (UC) enzymatic activity are insufficient to accurately evaluate this pathway in biological specimens where lower UC is expected. Liver cell lines, including HepaRG, have been described to have limited nitrogen fixation through the UC, limiting their applicability as biocomponents for Bioartificial Livers (BAL). This work aims to develop novel and sensitive analytical solutions using Mass Spectrometry-based methodology to measure the activity of four UC enzymes in human liver and HepaRG cells. Activity of carbamoyl-phosphate synthetase I (CPS I), ornithine transcarbamylase (OTC), argininosuccinate lyase (ASL) and arginase (ARG I and II) was determined on homogenates from normal human liver and HepaRG cells cultured in monolayer or in the AMC-BAL. Enzyme products were determined by stable-isotope dilution UPLC-MS/MS. Activity of CPS I, OTC and ARG I/II enzymes in HepaRG monolayer cultures was considerably lower than in human control livers albeit an increase was achieved in HepaRG-BAL cultures. Improved analytical assays developed for the study of UC enzyme activity, contributed to gain understanding of UC function in the HepaRG cell line. The decreased activity of CPS I suggests that it may be a potential rate-limiting factor underlying the low UC activity in this cell line.
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PMID:Advances in methods for characterization of hepatic urea cycle enzymatic activity in HepaRG cells using UPLC-MS/MS. 2875 91